Asthma is a common disorder among children. Children with asthma have multiple and complex environmental exposures, including inhalable pollutants and allergens. The response to inhaled exposures is characterized by airway inflammation, and possibly by activation of oxidative stress pathways. In theU.S., the burden of asthma is enormous, with a disproportionate impact on vulnerable groups including young children, African-Americans and those living in the inner city. These most vulnerable people often inhabit an environment that has excessive outdoor pollution levels, as well as high levels of indoor allergens and pollutants. We plan to address the critical questions of the role of the indoor environment on childhood asthma, we propose a panel study of children living in urban neighborhoods enriched with African-American and lower income participants. This real world field-based study will complement the findings from Projects 2, 3 and 4, which will similarly examine the effects of PM and allergen, but in controlled settings using human subjects, animal models and cell systems. We will recruit atopic asthmatics, including those with and without sensitization to mouse allergen, as well as normal controls, to address the following Specific Aims: Aim 1 .A: To determine the contribution of indoor PM to day-to-day variation in lung function and asthma control, among inner city children with atopic asthma. Aim IB: To determine if higher indoor PM exposure is associatedwith biomarkers of inflammation and oxidative stress. Aim 2A: To determine if mouse IgE-positive asthmatics with high mouse allergen exposure have greater susceptibility to PMthan other atopic asthmatics (mouse IgE-negative and/or with low mouse allergen exposure). Aim 2.B: To determine if mouse IgE-positive asthmaticswith high mouse allergen exposure (> 0.5 ug/g of Mus m 1) have elevated biomarkers of inflammation and oxidative stress in response to PM compared to those who are mouse IgE-E negative or who have low mouse allergen exposure..